Method, device and system for reducing off-axial aberration in electron microscopy

Abstract

A method for electron microscopy comprises: adjusting at least one of an electron beam and an image beam in such a way that off-axial aberrations inflicted on at least one of the electron beam and the image beam are minimized, the adjusting performed by using a beam adjusting component to obtain at least one modified image beam, wherein the adjusting comprises applying both shifting and tilting to at least one of the electron beam and the image beam and wherein the amount of tilting of at least one of the electron beam and the image beam depends on the amount of shifting of at least one of the electron beam and the image beam respectively and wherein the amount of tilting is computed based on at least one of coma and astigmatism introduced as a consequence of the shift.

What is claimed is: 
     
       1. A method for electron microscopy comprising:
 providing an electron microscope comprising a sample component, a beam generator, and a beam adjusting component; 
 securing a sample by using the sample component; 
 generating an electron beam by using the beam generator; 
 generating an image beam by directing the electron beam to the sample component; and 
 adjusting at least one of the electron beam and the image beam in such a way that off-axial aberrations inflicted on at least one of the electron beam and the image beam are minimized, the adjusting performed by using the beam adjusting component to obtain at least one modified image beam, wherein the adjusting comprises applying both shifting and tilting to at least one of the electron beam and the image beam and wherein the amount of tilting of at least one of the electron beam and the image beam depends on the amount of shifting of at least one of the electron beam and the image beam respectively and wherein the amount of tilting is computed based on at least one of coma and astigmatism introduced as a consequence of the shift. 
 
     
     
       2. The method of  claim 1 , wherein the adjusting comprises at least shifting of up to 3 μm, or up to 5 μm, or up to 10 μm of at least one of the electron beam and image beam. 
     
     
       3. The method of  claim 1 , wherein the adjusting comprises shifting and tilting the electron beam and the image beam and wherein
 the shift of the image beam is substantially equal and opposite to the shift of the electron beam; and 
 the tilt of the image beam is substantially equal and opposite to the tilt of the electron beam. 
 
     
     
       4. The method of  claim 1 , wherein the providing of the beam adjusting component comprises providing a beam adjusting component comprising electrostatic quadrupoles, wherein the electrostatic quadrupoles reduce astigmatism created by shifting at least one of the electron beam and image beam. 
     
     
       5. An electron microscope comprising:
 a sample component configured to receive a sample; 
 a beam generator configured to generate an electron beam; 
 wherein the electron beam is configured to generate an image beam upon being directed to the sample component; 
 a beam adjusting component configured to adjust at least one of the electron beam and the image beam to obtain at least one modified image beam, the beam adjusting component comprising at least a pair of beam deflectors and a pair of image deflectors, each pair configured to at least one of shift and tilt the electron beam and the image beam respectively; 
 wherein the beam adjusting component is further configured to minimize off-axial aberration inflicted on at least one of the electron beam and the image beam by adjusting at least one of the electron beam and the image beam to obtain at least one modified image beam, the adjusting comprising applying both shifting and tilting to at least one of the electron beam and the image beam, wherein the amount of tilting of at least one of the electron beam and the image beam depends on the amount of shifting of at least one of the electron beam and the image beam respectively and wherein the amount of tilting is computed based on at least one of coma and astigmatism introduced as a consequence of the shift. 
 
     
     
       6. The electron microscope of  claim 5 , wherein the beam adjusting component is configured to shift and tilt the electron beam and the image beam and wherein
 the shift of the image beam is substantially equal and opposite to the shift of the electron beam and 
 the tilt of the image beam is substantially equal and opposite to the tilt of the electron beam. 
 
     
     
       7. The electron microscope of  claim 5 , configured to operate without an inbuilt image corrector introducing a shift-dependent tilt to reduce off-axial coma. 
     
     
       8. The electron microscope of  claim 5 , wherein the beam adjusting component comprises electrostatic quadrupoles that are configured to reduce astigmatism created by shifting at least one of the beam and image beam. 
     
     
       9. A method for electron microscopy comprising:
 adjusting at least one of an electron beam and an image beam in such a way that off-axial aberrations inflicted on at least one of the electron beam and the image beam are minimized, 
 wherein the adjusting is performed by using a beam adjusting component to obtain at least one modified image beam wherein the adjusting comprises applying both shifting and tilting to at least one of the electron beam and the image beam, and 
 wherein the amount of tilting of at least one of the electron beam and the image beam depends on the amount of shifting of at least one of the electron beam and the image beam respectively and wherein the amount of tilting is computed based on at least one of coma and astigmatism introduced as a consequence of the shift.